New findings in immune system may hold the key to the survival of amphibians
2008 has been declared the year of the frog by the Association of zoos and aquariums marking major efforts to combat the amphibian extinction crisis. The frog and other amphibians form a vital part of the global ecosystem and give an indication of the overall health of the environment. Unfortunately however, close to 50% of amphibians are facing extinction. However, European researchers may have found the key to reversing this decline. Scientists worldwide are at a loss to fully explain the sudden and drastic collapse of amphibian populations. All they know is that the unprecedented rapid spread of infectious diseases such as the fungal infection Chytridiomycosis, is a major cause. The infection stems from the chytrid fungi, in particular the Batrachochytrium dendrobatidis variant of the fungi. This fungi is originally thought to have originated in South Africa. Once introduced to a new area, it spreads through water courses and amphibian to amphibian contact and thrives in moist cool habitats. Currently the fungus cannot be stopped in the wild and only a minority of species seem able to survive with an infection as either larvae or as adults. Once infected, these animals serve as a reservoir and as vectors for future outbreaks. Not all amphibians are susceptible however, and marine toads, American bullfrogs and African clawed frogs are highly resistant to it. Conservation efforts may however have a new ally in their fight to preserve the amphibian wildlife. Researchers from the Jagiellonian University in Krakow, Poland and from the Helmholtz Centre for Environmental Research (UFZ) have been characterising the genetic mark-up of amphibians and they have found more than one Major Histocompatibility Complex (MHC) class two locus in a tailed amphibian. These genes are vital for the auto-immune system of amphibians as they produce proteins that are crucial in fighting pathogen assault. What this means is that the genes are able to recognise and fight diseases as they occur. Up until now not much was known about the immune defence of amphibians. The thinking prior to this study was that the MHC gene was not particularly important. The study conducted by these researchers has however overturned this theory. The lead author of the study was Wieslaw Babik who conducted this research as part of a collaborative project between the University of Krakow and the UFZ in Halle-Saale. The study was financed by the Alexander von Humboldt Foundation and the findings were published in the journal of Molecular Ecology. For their research, the scientists studied various populations of the Alpine newt (Mesotriton alpestris) in Poland. The Alpine newt is the first European tailed amphibian species in which the MHC has been studied, and the first one in which more than one MHC II locus has been found. The research also built upon previous DNA studies which were able to show that the Polish population of the Alpine newt were able to achieve a high level of genetic diversity comparatively quickly in its 10 000 year history.
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